Therapeutic benefits can be achieved in some instances by providing an active agent to a specific target tissue, instead of systemically. This is because the effect of the agent on the target tissue can be maximized while limiting side effects on other tissues. Therapeutic benefits can also be achieved by providing an active agent to a subject in a manner that extends the time over which the active agent is released. One approach to providing these benefits is to use a coating system containing an active agent on a medical device.
Predictability and consistency of the elution rate of an active agent from a coating or material on devices is of importance, particularly in the clinical context. Specifically, in some applications it can be problematic if two devices manufactured in the same batch have significantly different elution rates, or if the elution rates vary significantly between separate batches. Finally, shelf stability of coated devices is of significance as an excessively short shelf-life may raise costs associated with maintaining an inventory sufficient to meet demand.
Accordingly, there is a need for coatings and methods of coating providing consistent elution rates. There is also a need for coatings and methods of coating providing adequate shelf-stability.